When not regulated effectively, stress has profound deleterious effects on several mental and physical health outcomes, such as triggering mood disorders and suppressing the immune system. Experiencing positive emotions in the midst of stress is one of the most promising and robust stress regulators, protecting people from succumbing to psychopathology as a result of stress and promoting adaptive stress responding. Despite our burgeoning knowledge of how the brain processes the potentially deleterious effects of stress and its associated negative emotions, no attempt has yet been made to identify the neural systems that support the potentially beneficial effects of positive emotions on stress and emotion regulation. This project will integrate psychological theories and neural models of positive emotions, stress, and emotion regulation to answer the question: Which neural systems support the beneficial effects of positive emotion on stress regulation? This project proposes a novel neuropsychological model that outlines the neural mechanisms that support the effects of positive emotions on successful stress regulation. From this model, three candidate neural mechanisms emerge that also map onto established psychological constructs. This project features a series of studies that investigates the engagement of these three systems in novel variations on validated experimental paradigms as well as in established behavioral paradigms adapted for the MRI scanner. Specific Aim 1 is to identify a safety mechanism by testing the hypothesis that positive emotions will aid in fear extinction via activation of the ventromedial prefrontal cortex. Specific Aim 2 is to demonstrate that positive emotions influence recovery from a single stressor through the adaptive meaning mechanism, and not through the simpler safety mechanism, by testing the hypothesis that positive emotions will shape stress appraisals by strengthening the functional connectivity between the ventromedial prefrontal cortex and the dorsomedial frontal cortex. Specific Aim 3 is to determine whether the established effects of positive emotion on cognitive reappraisal are due to the adaptive meaning making mechanism in the medial frontal cortex or to a cognitive facilitation mechanism in the lateral frontal cortex. Our studies will be conducted by undergraduate and master's students across two universities and will feature innovative MRI methodological/statistical approaches including temporal dynamics, functional connectivity, and mediational path analyses. The goals of this grant are to 1) significantly advance our knowledge of the different neural systems that support the effects of positive emotion on stress regulation, and 2) significantly strengthen the research environment at our universities by training students in advanced stress regulation and neuroimaging research.